The invention concerns a strand guide for a continuous casting plant, which comprises at least two segments, especially roll segments, each with a strand run-in end and a strand run-out end and with a pair of roll supports, which support a number of containment rolls that extend over a containment zone and which can be adjusted by adjusting units, especially hydraulic adjusting units.
The strand guide of continuous casting plants is characterized by the well-known segmental construction. In designs for hydraulic adjustments of segments, for example, for a change in section thickness, soft reduction, or other necessary position-regulated gap-width adjustments that require a continuous strand thickness reduction, each of the segments is adjusted independently of the other segments with two pairs of hydraulic cylinders comprising four individual hydraulic cylinders. An exception here is the first segment in thin slab continuous casting plants, which is equipped with only one pair of cylinders, because a bending point is usually located on the run-in side below the mold.
In the state of the art, a series of practical designs for guiding a strand and suitable strand guides for this purpose are known.
The document WO 98/00,253 describes a method for guiding a strand, especially a steel strand, in a continuous casting plant with a soft reduction zone, in which servo units provide continuously variable adjustment of the gap width between opposing strand guide rolls. In a strand guide segment with four servo piston-cylinder units, two adjacent cylinder units, which are hydraulically linked with each other, are adjusted to the strand, and the remaining cylinder units are independently subjected to continuously variable adjustment. The position of the two cylinder units that are linked is detected, compared with set points, and controlled according to preset data and a mean value. When defined distance values are exceeded, another pair of servo piston-cylinder units is linked together.
The document WO 99/46,071 concerns a method for adjusting a roll segment of a continuous casting plant, which has a segment run-in end, a segment run-out end, and a pair of roll supports, each of which supports rolls that extend over a support zone, such that the roll supports are mutually adjusted against each other by an adjusting unit installed at the segment run-in end and an adjusting unit installed at the segment run-out end, and such that each adjusting unit has two hydraulic cylinder units arranged on either side of the support zone. The hydraulic cylinder units can be adjusted both by position regulation and pressure regulation. The rolls are adjusted to a metal strand guided by the rolls by the hydraulic cylinder units by means of position regulation, and the hydraulic cylinder units are changed over from position-regulated to pressure-regulated operation when the pressure in the given hydraulic cylinder unit reaches a threshold value.